Frederick T. Frelinghuysen was born in Millstone,
New Jersey on August 4, 1817. He entered Rutgers
College as a sophomore and graduated in 1836.
Upon graduation, he studied law in Newark
with his uncle. After three years of study
he was admitted to the New Jersey Bar in 1839.

He was appointed Counsel of the New Jersey
Central Railroad Company, as well as the Morris
Canal and Banking Company. In 1861, Governor
Olden appointed Frelinghuysen Attorney General.
When his term expired, Frelinghuysen was reappointed
for a new term. In 1867, he was elected as
a Republican to the U.S. Senate to fill the
vacancy caused by the death of William Wright.